Objectives: This study tested the reliability and validity of the Western Canada Waiting List Project priority criteria score (PCS) for prioritizing patients waiting for hip and knee arthroplasty.

Methods: Sixteen orthopedic surgeons assessed 233 consecutive patients at consultation for hip or knee arthroplasty. Measures included the PCS, a visual analogue scale of urgency (VAS urgency), and maximum acceptable waiting time (MAWT). Patients completed a VAS urgency, an MAWT, the Western Ontario McMaster Osteoarthritis Index (WOMAC), and the EQ-5D. Using correlational analysis, convergent and discriminant validity was assessed between similar constructs in the priority criteria and WOMAC. Median MAWTs were determined for five levels of urgency based on PCS percentiles. Internal consistency reliability was assessed with Cronbach's alpha.

Results: The sample of 233 patients (62 percent female) ranged in age from 18 to 89 years (mean, 66.3 years). A total of 45 percent were booked for hip and 55 percent for knee arthroplasty. Correlations were strong between the PCS and surgeon VAS urgency (r=.79) and weaker between patient and surgeon measures of VAS urgency (r=.24) and MAWT (r=.44). Correlation coefficients between similar constructs in the priority criteria and WOMAC ranged from 0.24 to 0.32 and were higher than those measuring dissimilar constructs. For decreasing levels of urgency, the median MAWT ranged from 10 to 12 weeks for surgeons and 4 to 12 weeks for patients. Cronbach's alpha was 0.79.

Conclusions: Results support the validity of the PCS as a measure of surgeon-rated urgency. Patients might be ranked differently with different prioritization measures.